New Frontiers in Energy Management
When facilities like wastewater treatment plants manage motor pumps, processes, and controls efficiently, customer relations improve along with operations.
By Penelope B. Grenoble
“Utilities continue to find it extremely challenging to fund and manage capital projects while keeping rates low and stable. They’re embarking on asset management programs while finding ways to reduce operating costs and increase revenues through energy-related projects. . . . These programs are increasingly delivered through public private partnerships with alternative means of financing,” says Steve Tarallo, North America Business Lead, Sustainable Water and Energy Solutions, Black & Veatch.
Energy management has become a matter of necessity in states like California, and less enthusiastically embraced in states where energy costs are lower. But take a closer look, and you’ll discover that energy and operational efficiency go hand in hand—and that managing energy costs goes beyond simply equipping a pump with a variable speed drive.
“In drinking water facilities, we’re looking at about 1,000 to 2,500 kilowatt-hours per million gallons of water treated,” says Barry Liner, Director of the Water Science & Engineering Center at the Water Environmental Federation (WEF). “On the wastewater side, we’re looking at 1,000 to 4,000 kilowatt-hours per million gallons.”
A Coordinated Approach
The Philadelphia Water Department (PWD) has a long history of energy management programs, including strategic load shifting to optimize cost reduction; purchase and installation of exclusively high-efficiency equipment (which involves paying a premium for better equipment and realizing the cost savings over its lifetime); in-house power generation; and peak load shaving/demand management.
“The kilowatt you don’t use is the best kilowatt,” says Paul Kohl, PWD Energy Program Manager. “During fiscal year 2013, PWD used approximately 274 million kilowatt-hours of electricity and 333,700 MBTUs of natural gas, for a total of 1,359,000 MBTUs worth of energy.” (In addition to potable water, the department handles the city’s wastewater and stormwater.)
“Our pump stations are extremely efficient,” says Kohl. “For decades, we’ve been moving water around the city at night. We trim impellers to get the right curves, we have our own maintenance facilities, and we do an estimated water-to-water efficiency per pump station per month, which the manager reviews to determine if the station is gaining or losing efficiency. If it’s losing, we determine which pump isn’t working well, and why. This is a constant operational activity. Our operators do it as part of their job, and they do it well and save us millions of dollars. We produce a very good buying profile, and we have a very predictable rate capacity. We have such control over our electricity that if you call a demand on us, we can reduce three megawatts of energy on five-minute’s notice.”
Chris Crockett, PWD Deputy Commissioner for Planning & Environmental Services, adds to the discussion. “What we’re talking about is the water/energy nexus. At the turn of this century, we looked at wastewater management as relatively routine. The wastewater industry was building tertiary treatment plants that suck energy off the grid, installing things like ultraviolet light and membrane technologies, which also pull off high amounts of energy, create residuals, and have a negative carbon footprint. That was the way the 20th century used advanced technology, continually drawing on more and more energy to make things better.”
PWD’s effort to offset energy consumption includes:
- a photovoltaic solar panel installation that generates over 300,000 kWh alternating current (AC) power production per year at the department’s Southeast Water Pollution Control Plant (WPCP);
- a sewage geothermal heat pump system, the first of its kind in the nation, which taps the wastewater stream at Southeast WPCP and uses the thermal energy to heat the plant’s compressor building and gallery space (heating capacity: 978,000 BTUs per hour, and cooling capacity: 60 tons);
- an aircraft deicing fluid codigestion program, which has generated 38,000 MBTUs of additional energy from increased biogas production and $134,000 in tipping fees since its inception in 2008; and
- a newly commissioned Biogas Cogeneration Facility.
“Rate caps had kept energy prices low following the passage of Pennsylvania’s Deregulation Bill in 2005, but these caps were set to expire at the end of 2010,” says Kohl. “And PECO [formerly Philadelphia Electric Co.] was moving from energy generation, transmission and distribution to transmission only. This motivated PWD to investigate electricity generation using the biogas produced in the anaerobic decomposition of organic material in our wastewater treatment plant digesters. The digester gas is pre-treated to remove water vapor, hydrogen sulfide, and siloxane gas burned in the generator engines, producing both electricity and heat. The cogeneration facility’s conversion of gas to electricity, combined with the recapture of waste heat, results in the capture of over 80% of the available energy from the gas.
“At full capacity,” continues Kohl, “the plant’s four 1.4-MW internal combustion stationary gas engines will produce 85% of the wastewater treatment plant’s current electric demand (15% of the PWD’s overall electric demand) and 100% of the wastewater treatment plant’s heating needs. The biogas cogeneration facility is a sustainable way to use an existing resource to generate power while helping to insulate the utility from the volatile energy market.”
To develop the project, the city issued a request for proposal (RFP) and formed a public-private partnership (P3) with successful bidder Ameresco and Bank of America. The arrangement called for Ameresco to procure financing and install, build, and commission the facility, which Bank of America owns, and the city will lease for 16 years to make use of the generated electricity and thermal heat. As is typical of these kinds of partnerships, the city has also entered into a long-term maintenance contract with Ameresco.
Because the Biogas Cogeneration Facility is P3 owned, it’s eligible for a $14.1 million ($13 million after sequestration) Investment Tax Credit Grant. The project also qualifies for over $3 million in State Act 129 funding, which will be issued directly to the city. This green power generation offsets 27,870 tons of carbon dioxide per year, which would be the equivalent of removing 4,833 passenger vehicles from the road, planting 5,390 acres of pine forests, not burning 132 railcars worth of coal, or simply not using 2.84 millions of gallons of gasoline.
A New Way of Thinking
“Typically, when you’re designing a water or wastewater plant, your goal is to get the water through,” says Paul Schuler, Region Executive for the Americas for Engineered Systems at General Electric. “You’re not looking at energy efficiency. Over time, this had led to things like over-sizing equipment such as pumps in water treatment and aeration blowers in wastewater. But, not only do utilities need to treat water to the specified drinking water quality or to a particular discharge quality in a wastewater plant, they also need to look at efficiency and how to use their overall resources.
“Whenever GE develops a product, we look at increasing energy efficiency,” explains Schuler. “Working with the City of Riverside, California, for example, we helped reduce its electricity bill by $75,000 a year with our new LEAP membrane bioreactor. The money we helped them save is specifically on the air scour process. Just making that one process more efficient allowed them to save a significant amount of money on their energy use.”
“The water industry has necessarily focused on the quantity and quality of water,” says Lee Ferrell, Business Development Manager at Schneider Electric’s Water Wastewater Competency Center. “But trying to implement energy management one piece at a time, or when you get around to it, isn’t the most productive way to be more energy efficient. A lot of utilities go to lighting first because it looks easy, but lighting doesn’t give you the big bang for your buck that aeration or pump optimization would. Utilities are often looking for quick turnarounds—three to five years—but if they adopt a more efficient way of running their pumps right now, 20 years from now their life cycle cost will be reduced.”
Saving Energy—A Better Way to Do Business
“Today, any responsible utility is looking at ways to save energy,” says Mark Gasvoda, Chairman and CEO at B.L. Anderson in Lafayette, IN, a distributor for ABB Inc. “It’s the responsible thing to do for their customers, and it should provide benefits in better operation and a more feasible way to do business. The opportunities today with VFD [variable frequency drives] and related instrumentation, computers, remote monitoring, and SCADA [supervisory control and data acquisition] equipment are just endless. We work with engineers and utilities using drives for energy efficiency in the water treatment business—most commonly with pumps, and in the wastewater business both with pumps and blowers, which tend to be the largest energy consumers in a wastewater plant.
“We always talk to our clients about understanding how the equipment will be used, which is one of the things we think is most important and sometimes gets lost,” says Gasvoda. “What type of motor will they be using the drive on; what are their needs for the range of that motor—how often is it at full speed, how often are they able to turn it down? Have they talked to the manufacturer to make sure they won’t damage the motor or piece of equipment by slowing it down? We want to understand how they pump, what their daily demands are, what they’re pumping to, and how their pressure curve may change throughout the day.”
He continues, “The idea is to use drives to keep pumps within their most efficient range, so that they only speed up and slow down to stay within a range that keeps them at peak efficiency. You can get a very wide range of adjustment with a drive that you’re not able to get on stroke length of pumps. You may get a 10 to 1 adjustment range by changing the length of the stroke, but you might get 100 to 1, or more, using a variable speed drive. Some people will use both and magnify the range that way. In Indiana and the Midwest, we have fairly low power costs, six/seven cents per kilowatt-hour. At six cents per kilowatt-hour, you will save roughly $400 per year per horsepower saved. You typically wouldn’t run 100-horsepower pumps at full horsepower, probably more like 85 horsepower. But if you could save 10% of that by better management, you have the ability to save 8 to 10 horsepower per year, which would save you $4,000 per pump.”
Mark Higginbottom, Energy Efficiency Manger for Rotary Equipment at Veolia Water North America, says, “Ultimately, your goal is to evaluate the entire system and the needs of the system, and not just an individual piece of equipment. In a water treatment plant, I look for inefficiencies in the pumps. Realizing that service pumps are the major energy consumers, I consider whether there is a better way to run them. Do they need to be rebuilt? Could I go with a smaller pump or put them on a variable speed drive?
“In a wastewater treatment plant, I look at the discharge pressure of the blower,” he continues. “Say it’s seven psi. I would then locate the original paperwork and maybe see it’s capable of nine psi, which tells me it’s over-designed. And then I’d look at how it’s being operated. Typically, a piece of equipment like a pump or a blower wants to operate unthrottled, which means it’s designed to have both the suction and discharge valves wide open. But, in this particular case, one of those valves was in a half-open position. When I asked why, the answer was to reduce flow, because they didn’t always need what the machine fully puts out. But, adjusting the blower or pump to restrict the amount of flow results in inefficiency in the system. We could look at a VFD, a new smaller blower, or possibly, a properly sized, high-speed turbo blower. The next step would be to go to various manufacturers, walk through the analysis, and then bundle it together to determine how much power is going to be saved, and present it to the client.”
“It’s not just using less energy, it’s paying less for what you do buy,” says Mark Leinmiller, Water Wastewater Segment Manager at Schneider Electric. “It’s being smart about lowering your overall demand and, certainly, the demand charges.
An employee may not know when they turn on a piece of equipment, that they could be setting a new demand threshold that could stick with the utility for the next 12 months.
“A lot of utilities really don’t have a very good grasp of what they have available,” adds Leinmiller. “Many have SCADA systems, which means they have a method of capturing data. Many probably have electronic metering that can give them at least the incoming main, so they have an idea of what their overall usage is. But the people who run the plants hardly ever see that information, so they don’t really know the impact of their actions. Establishing this baseline and putting a context to it is relatively simple to do, remembering that it’s not just kilowatt-hours, but kilowatt-hours related to the flows. This will give you some kind of sense of what it’s costing to run your facility.
“One of the things we’ve found in larger municipalities is wastewater operations can be half of their overall energy use, which means if they’re looking for energy savings, they should look there,” he adds. “In Denison, Texas, for example, the wastewater treatment plant was built back in the ‘80s, really hadn’t been updated, and was very inefficient. The city elected to move forward on multiple improvements by leveraging energy savings guaranteed with a performance contract that included new equipment in the wastewater treatment plant, HVAC replacements and lighting retrofits, and a new citywide energy management system. We helped them apply for a $64,000 rebate for the HVAC and lighting, and approximately another $165,000 for the process improvements at the wastewater plant. Bundling the smaller projects with the wastewater treatment plant upgrades made it possible for them to do a number of projects that they had a hard time justifying as a cost investment by themselves.”
Wes Lobo at Xylem/Flygt supports Leinmiller’s point about educating employees on the effects of their actions. The company recently established its Total Care after-market group, which proactively evaluates customers’ equipment and looks for opportunities to provide service.
“Ongoing training has turned out to be one of our customers’ biggest needs,” he says. “It’s the nuances of a system that are important, things that may seem fairly trivial but are important to how efficiently it’s running. Municipal contracts are written with specs for start-up testing and commissioning training, but it can be difficult to cover all shifts and everyone on them. And six months later—especially if it’s a utility that has multiple water or wastewater sites—your trained operator may go to a different site. It’s important to make your staff aware of the impact of what they’re doing. It’s not just about teaching them how to operate a PLC [programmable logic controller] panel or how to turn a wrench to fix a pump. It’s about making them aware of the impact their decisions have on the big picture.
“When we first started Total Care, we discovered that, although the PLC is set up for optimum efficiency, operators were flipping the switch to manual and turning it up to 100% power,” adds Lobo. “The plant might be running at 20% of flow, but they’re running the UV system at 100% power. That not only wastes energy, it wastes consumables.”
Under a state mandate to cut electricity use by 5% annually, the City of Fort Worth had worked with Johnson Controls Inc. (JCI) to reduce consumption in areas such as facilities and transportation, but had come up short. To help meet its energy reduction requirements, it decided to take a look at its wastewater operations, in particular the 166-MGD Village Creek Water Reclamation Facility, which was chewing up 10 MW of energy.
“We visited their facilities to get an understanding of their operations and goals,” says JCI’s Project Development Consultant Peter Cavagnaro. “We identified areas where energy was being used, talked with the staff about the facility and equipment they wanted to update in the coming years, and developed a shortlist we called Facility Improvement Measures for the Village Creek plant. It turned out that a lot of our recommendations lined up with what the city had already hoped to do.”
In approximately 1999–2000 in an initial step toward energy management, the city had installed two 5.2-MW gas-powered turbines at the plant to replace reciprocating engines that were old and no longer functional. “We were using the methane gas from the digesters and from a local landfill to fire one of the turbines,” says Assistant Director Buster Fichera. “By 2005, we were producing 42 to 45% of the energy the plant required at that time. What JCI saw was an opportunity to capture the waste heat from the turbine to generate steam that could be used to drive two of the plant’s blowers. We were also interested in developing a way to receive high-strength waste to improve the amount of methane gas we needed to fire the turbines and duct burner associated with the Heat Recovery Steam Generator.”
He goes on to say, “Essentially, we leveraged the ability of gaining electrical efficiency with the need to make improvements to the plant and getting the most for our investment. That was a huge factor in the decision to proceed with the energy efficiency project at Village Creek.”
“With the performance contract we entered into with JCI, we were able to make improvements and have them pay for themselves with the electricity savings,” says Project Engineer Madelene Rafalko. “Instead of borrowing money for a capital project, we were effectively self-funding these improvements.”
“Every time we do something with respect to energy, we find that it opens other avenues,” explains Fichera. “When the steam that’s being used to drive two of our blowers comes out from the blowers, it still has some functional use as an additional heat source for sludge drying, thereby reducing our solids disposal costs. We are currently only using one turbine at a time, but now that we have an ample supply of gas from our anaerobic digesters and from the nearby landfill, we’re thinking about operating the second turbine and possibly starting to put that extra energy back on the grid, creating net-zero energy for ourselves and possibly assisting with energy at some of our other facilities.”
“Energy in our area is only 6.5 cents a kilowatt-hour,” says Linda Daly, Director of Jefferson Parish Department of Sewerage in Jefferson Parish, LA. “But with the state Clean Water Revolving Loan Fund, 20% of the principle is forgivable for energy and water conservation projects. We had a submersible station where we were pulling the pumps every day because of ragging and grease problems. If you’ve got a clogged pump, as it’s starting to clog and losing efficiency, you’re using up more energy. It was also costing us a lot of manpower and overtime calling out crews in the middle of the night to unclog pumps.”
To address both problems, Xylem/Flygt distributor Gulf States Engineering installed the recently introduced Flygt Experior pump system in a number of the most affected pump stations. The first station received only the Experior system’s Adaptive N-pump while three other lift stations were equipped with SmartRun controls. At initial installation, one of the pumps operated at an energy consumption rate proportional to the initial startup frequency of 60 Hz. The SmartRun controls automatically identified the targeted optimal speed and adjusted to 38 Hz after only two days of operation. After a year the stations are experiencing approximately a 50% reduction in energy use.
“Energy savings and energy efficiency go hand-in-hand,” says Daly. “Maybe energy may not save us that much money right now, but going forward it probably will. We expect in the future to see our energy prices go up like everybody else’s, so we’re looking toward the future by doing some other energy-efficient projects with variable speed drives, smart controllers, premium efficiency motors, and other types of pumps, including vertical turbines.
“We’re partnering with the University of New Orleans on an energy study to determine where we’re using the most energy and what we can do to reduce our energy costs,” she continues. “We’re paying for the study through our budget, but as we identify things we can do, we’re going to go after federal or state money, or whatever money we can get, to actually build the projects. Partnering with the university, we’ll get a really good product for a whole lot less than paying an engineering firm, and we’re helping the university and the PhD student who will be doing the study.”
Assessing the System
It may be all well and good to think in terms of process rather than individual pieces of equipment, but what’s the best way to go about it?
“There’s a wide variety of sophistication in terms of energy management at water utilities,” says Edward Spang, Program Manager at the UC Davis Center for Water-Energy Efficiency in Davis, CA. “What we’re hoping to do is come up with some streamlined data analysis and develop software to help utilities visualize their energy use better.
“The challenge in the systems approach is really lining up data that sometimes is fragmented within a water utility and putting it together in such a way that it becomes actual information,” he adds. “There are also other systems-based analysis you can do, such as leak protection and assigning kilowatts saved by saving a million gallons through leaks. Another piece might be operating your pumps as a system more effectively to gain efficiency rather than replacing component pumps within the system.
“In California right now,” continues Spang, “the Public Utilities Commission is pushing energy IOUs to expand the vision of where to gather energy efficiency opportunities and where to implement projects. However, the water utility sector is not accustomed to that level of data in terms of energy analysis to readily partner with the energy utilities. So, we’re trying to help facilitate that conversation by helping water utilities organize and present their data in a way that it’s readily usable by the energy utilities to help design programs.”
If your challenge is in wastewater, the Water Environmental Federation (WEF) has developed a framework to guide municipalities down the road to sustainable energy management through increased renewable energy production, energy conservation, and a focus on overall energy management. The Energy Roadmap is applicable whether plants choose simply to increase energy efficiency, or to build a full-scale cogeneration system. The steps are arranged under various topics, from technical needs to managerial aspects, and are applicable to small, medium, and large facilities.
“The roadmap helps you to look at energy efficiency in relation to energy generation and strategic management and organizational culture in order to focus on resource recovery and sustainable energy management,” says Liner at WEF. “You have innovation and risk management issues as well. That’s why we developed this framework; so it doesn’t seem as daunting to the utilities.”
“You can do an audit,” explains Leinmiller at Schneider Electric, “but the challenge I have with audits is that they tend to sit on a shelf and gather dust. What you really need is an energy action plan, which has buy-in at the high and low levels of your organization, the awareness that energy is a priority and you’re going after it. We’ve done projects where very low—and possibility no—upfront capital is required to see some pretty significant savings, which effectively are paying for themselves.”
“Utilities are faced with a number of challenges today that include rapidly increasing energy and chemical operating costs, an aging work force, as well as ever increasing environmental regulation,” says David Wrightsman, Senior Energy Engineer with Energy Systems Group. “Many of them are interested in a business-minded approach to improve organizational and systemwide efficiency that transcends a single piece of equipment but encompasses an overall look at systems and process to drive out inefficiencies and seek out new revenue streams. An ESPC [Energy Savings Performance Contract] may provide the means to accomplish that.
“In most cases,” he adds, “the ESCO [energy service company] will partner with a consulting engineering company and various contractors to install the work. The owner may retain counsel or an engineering firm to advise him on complex projects and act as a third-party inspector to ensure his interests are being represented during contract negotiation and construction. Many owners provide those services in-house. Careful thought needs to go into the measurement and verification of the savings after construction. Water and wastewater facilities are dynamic and will change over the term of the guaranteed contract, so the measurement and verification techniques need to be flexible enough to accommodate changes while still resolving the energy savings. Means and methods for making changes to baselines need to be spelled out and agreed to in advance of needing to make the changes.”
Wrightsman emphasizes that contract details need to be carefully laid out, from overall goals or performance metrics to letter specific details for the work to be completed. “Staff turnover happens constantly at utilities, so it is important to maintain strong contract documentation of the work implemented.”
“We need to keep encouraging the water and wastewater industry to leave its comfort zone and interact with the changes the world, and our customers, are forcing on us,” says Crockett at the Philadelphia Water Department.
What’s next for Philadelphia? Algae, among other things. “My dream is that eventually someday wastewater facilities will be mini refineries,” he says. “We’ll be growing algae and producing biofuels and nutraceuticals. Whatever we do has to pass the chuckle test. If people chuckle, you have to go back and think about it and come back with the hard facts. But the baseline is ‘just do it.’ The energy and communications industries have been dealing with very similar issues but from a different perspective. By combining that perspective and their knowledge and experiences, we should be able to identify a whole new generation of approaches and technologies to address our challenges in water and wastewater.”
Author’s Bio: Penelope B. Grenoble is a frequent contributor to Forester Media.